This invention generally relates to valve mounting assemblies for aerosol containers, said mounting assemblies being commonly referred to as xe2x80x9cmounting cupsxe2x80x9d. More particularly, this invention relates to a particular tubular gasket (sleeve gasket) for the mounting cup, which varies dimensionally from prior sleeve gasketed mounting cups. Further, during a certain interval of the positioning of the sleeve gasket onto the mounting cup, the sleeve gasket varies in its spatial relationship with the mounting cup as compared to prior sleeve gaskets.
Aerosol containers are widely used to package a variety of fluid materials, both liquid and powdered particulate products. Typically, the product and a propellant are confined within the container, at above atmospheric pressure, and the product is released from the container by manually opening a dispensing valve to cause the pressure within the container to deliver the product through the valve and connecting conduits to a discharge orifice.
The dispensing valve is normally mounted in a container opening via a mounting assembly that includes a mounting cup and sealing gasket. More particularly, the container includes a top opening or bead portion. The mounting cup includes a central pedestal portion for clinching the dispensing valve, a skirt portion extending from the pedestal portion, which skirt portion merges into a radially outwardly extending channel portion, the channel portion being configured to receive the rounded bead portion of the container opening. The sealing gasket normally extends along a part of the skirt portion and to a limited degree into the channel portion. After the sealing gasket is disposed onto the mounting cup, the cup is positioned onto the container and the cup is clinched to the container. The clinching operation is well-known to those skilled in the aerosol container art.
Obviously, for an aerosol container, the seal between the mounting cup and the container bead is critical. This seal is accomplished through the sealing gasket, which must prevent the loss of pressure and loss of container contents through the interface between the container bead and mounting cup.
Various types of sealing gaskets are known in the art. One common type of gasket comprises a conventional flat rubber gasket that is placed inside the channel of the mounting cup. Gaskets of this type are typically manufactured by extruding and vulcanizing the compounded rubber mixture onto metal rods and then cutting or slicing off thin, annular sections of the extruded and vulcanized product (tube). These gaskets are often referred to as cut or flat gaskets. Cut gaskets are relatively expensive to manufacture. It is very difficult to control precisely the radial dimensions of the tubes, from which the cut gaskets are made, the tubes having varying dimensions and being out of round. Consequently, the inner and outer cylindrical surfaces of these tubes are usually laser cut to the desired dimensions, said cutting adding considerable cost to the gasket manufacture.
Another type of gasket comprises a relatively thin sleeve of elastomeric material that is mounted on the skirt portion of the mounting cup and then advanced along said skirt so that the gasket extends ultimately into a limited portion of the annular channel of the mounting cup. When the mounting cup is mounted and then clinched onto the aerosol container, the sealing gasket is forced into a sealing engagement with both the channel of the mounting cup and the bead of the container. Typically, these gaskets are forced into a sealing engagement with the mounting cup along only a relatively small circumferential portion of the gasket at positions referred to as the 5 o""clock and 11 o""clock positions. Due to their shape, gaskets of this type are often referred to as sleeve gaskets.
Sleeve gaskets are manufactured by advancing a tube of gasket material onto the skirt of the mounting cup and then cutting or slicing off annular sections of the tube. The axial heights of sleeve gaskets, however, are substantially greater than the axial heights of cut gasket. Sleeve gaskets are much less expensive to make and assemble to the mounting cup than cut gaskets. When making sleeve gaskets, it is not necessary to mill the inside and outside cylindrical surfaces of the extruded tubes of gasket material. Moreover, a tubular sleeve gasket may be assembled to the mounting cup more easily than assembling a cut gasket to the mounting cup.
The sealing gasket may also be formed by a liquid material containing water or solvent that is deposited in the annular channel of the mounting cup. The solvent or water evaporates during curing and the remaining material produces a resilient sealing material in the mounting cup channel. Forming the gasket from a liquid solvent also is a comparatively expensive procedure requiring multiple production steps including the use of curing ovens or other means to dry and cure the gasket material. Moreover, means must be provided for rotating the mounting cup beneath and relative to a metering apparatus that dispenses carefully determined amounts of a gasket forming composition. These gaskets are commonly referred to as xe2x80x9cflowed-inxe2x80x9d gaskets.
Thus, the above described types of gaskets, as well as others that may be used, have both advantages and disadvantages. Both cut and sleeve gaskets generally produce excellent results. Cut gaskets have seen widespread commercial use for a longer period of time than sleeve gaskets. To use sleeve gaskets on equipment previously used with flat or cut gaskets requires an adjustment in the crimping and filling tools. Often, a crimping line will be required to accommodate both flat and sleeve gaskets; depending on the gasket specifications of the valved container being crimped. To avoid having to make the crimping and filling change or adjustment, there has been a tendency, particularly in Europe, to stay with flat or cut gaskets, even though such gaskets are more costly.
An object of this invention is to provide an improved gasketed mounting cup for aerosol containers and an improved method for assembling the gasket to the mounting cup.
Another object of the present invention is to provide a mounting cup for an aerosol container with a sealing gasket that has the cost advantages of a sleeve gasket but that allows the crimping and filling equipment to be used at the same settings for the clinching and filling of a cut gasket.
A further object of this invention is to position a sleeve gasket on a mounting cup so that the gasket has dimensions equivalent to a flat or cut gasket without requiring any milling of the gasket material.
Another object of this invention is to provide a novel sleeve gasket disposed on a substantial portion of the skirt of the mounting cup such that during the affixment of the mounting cup and container, the sleeve gasket may be advanced into the channel portion of the mounting cup.
These and other objectives are attained with a valve mounting assembly for an aerosol container comprising a mounting cup and a relatively thick sleeve gasket of limited height positioned on the mounting cup.
The sleeve gasket of this invention is positioned onto the skirt portion of the mounting cup and then ultimately advanced into the annular channel of the mounting cup prior to clinching the mounting cup and container. The advancing of the sleeve gasket of this invention prior to the clinching operation results in a deformation of the gasket of about 90xc2x0 to form a gasket comparable in shape and dimension to a conventional cut gasket. The sleeve gasket of this invention may be cut from an extruded tube of gasket material, which can be cut to very precise longitudinal dimensions. When the sleeve gasket is turned about 90xc2x0 into the channel of the mounting cup, the original axial dimension of the gasket becomes its radial dimension or thickness. In this way, a cut gasket shape can be achieved having precise inner and outer dimensions without requiring the costly processing of the gasket material, as has been previously required with prior art cut gaskets.
The sleeve gasket may be advanced onto the skirt of the mounting cup and then advanced into the annular channel thereof in one operation but preferably it is done in two separate steps. For instance, the sleeve gasket may be advanced onto the skirt of the mounting cup at one location and sold in this condition to a manufacturer of filled aerosol containers, who then advances and deforms the gasket into the desired shape in the annular channel of the mounting cup.
Where the sleeve gasket is disposed on the skirt portion, or at least a substantial portion of the sleeve gasket is disposed on the skirt of the mounting cup and transferred in this form to another location, there is the advantage that the friction fit between the skirt of the mounting cup and the sleeve gasket is adequate to prevent dislodgement of the gasket from the mounting cup during transport and storage prior to the clinching of the gasketed mounting cup and the container, a problem often present in the transportation and storage of cut gaskets.
Where, however, it is desired to dispose the sleeve gasket of this invention normal to the axial length of the skirt of the mounting cup, means or steps may be used to maintain or to hold the gasket in the deformed shape in the channel of the mounting cup. Any suitable means may be used to advance and deform the gasket into the desired shape in the mounting cup channel and to maintain the gasket in the channel. For example, the aerosol container itself may be used to do this as the mounting cup is disposed onto the filled container or adhesive may be used to bond the deformed gasket to the channel of the mounting cup.
Further benefits and advantages of the invention will become apparent from a consideration of the following detailed description given with reference to the accompanying drawings which specify and show preferred embodiment of the invention.